Ultrasound vs Clinical Parameters for Difficult Airway Prediction in Obesity

NCT07528677 | Not Yet Recruiting

• 1 other identifier: FSMAİRWAY
• Study Type: observational
• Target: 70
• Locations: 1 country
• Sites: 1

Brief Summary

Obesity is associated with anatomical changes in the upper airway that increase the risk of difficult laryngoscopy and difficult mask ventilation during anesthesia. Conventional airway assessment parameters such as Mallampati score, neck circumference, and STOP-BANG scale are widely used but have limited predictive accuracy in obese patients. Airway ultrasonography has emerged as a promising non-invasive tool for difficult airway prediction; however, ultrasonographic criteria have not yet been standardized. This prospective observational study aims to evaluate the utility of airway ultrasonography in predicting difficult airway in adult obese patients (BMI \>30 kg/m²) scheduled for elective surgery under general anesthesia. Ultrasonographic measurements will include the distance from skin to hyoid bone (DSHB) at the level of the hyoid bone, the anterior neck soft tissue thickness at the thyrohyoid membrane level, and the hyomental distance ratio (HMDR). These parameters will be compared with conventional airway assessment tools and correlated with intraoperative Cormack-Lehane laryngoscopy grade and Han Scale mask ventilation score to determine their predictive value for difficult airway.

Conditions

Obesity (BMI > 35); Difficult Airway; Difficult Airway Intubation; Difficult Mask Ventilation

Keywords

Airway ultrasonography; Difficult airway prediction; Obese patients; Cormack-Lehane classification; Han Scale; Hyomental distance ratio; Distance from skin to hyoid bone; Neck circumference; Mallampati score; STOP-BANG scale; General anesthesia; Orotracheal intubation

Outcome Measures

Primary Outcomes (1)

• Correlation of Ultrasonographic Airway Parameters (DSHB and HMDR) with Cormack-Lehane Laryngoscopy Grade

  Preoperative ultrasonographic measurements including the minimum distance from skin to hyoid bone (DSHB) at the hyoid bone level and the hyomental distance ratio (HMDR, calculated as hyomental distance in full extension divided by hyomental distance in neutral position) will be correlated with the intraoperative Cormack-Lehane laryngoscopy grade. Cormack-Lehane grades III and IV will be defined as difficult laryngoscopy. The diagnostic accuracy of DSHB and HMDR in predicting difficult laryngoscopy will be assessed using ROC curve analysis.

  Perioperative/Periprocedural

Secondary Outcomes (2)

• Predictive Value of Conventional Airway Parameters for Difficult Laryngoscopy

  Perioperative/Periprocedural

• Predictive Value of Ultrasonographic and Conventional Airway Parameters for Difficult Mask Ventilation

  Perioperative/Periprocedural

Study Arms (1)

Obese Patients Undergoing General Anesthesia

Adult obese patients (BMI \>30 kg/m², aged 18-65 years, ASA I-III) scheduled for elective surgery requiring orotracheal intubation under general anesthesia. Preoperative airway assessment will include conventional parameters (Mallampati score, neck circumference, STOP-BANG scale) and airway ultrasonographic measurements (distance from skin to hyoid bone \[DSHB\] and hyomental distance ratio \[HMDR\]). Standard anesthesia induction will be performed with propofol 2 mg/kg, fentanyl 2 mcg/kg, and rocuronium 0.6 mg/kg. Mask ventilation difficulty will be graded using the Han Scale and laryngoscopy difficulty using the Cormack-Lehane classification. Anesthesia will be maintained with sevoflurane and remifentanil infusion targeting BIS 40-60.

Diagnostic Test: Airway Ultrasonography

Interventions

Airway Ultrasonography DIAGNOSTIC_TEST

Preoperative airway ultrasonography will be performed by a trained anesthesiologist using a linear ultrasound probe with the patient in the supine position and head in neutral position. The following measurements will be obtained: (1) minimum distance from skin to hyoid bone (DSHB) at the transverse view of the hyoid bone level, (2) anterior neck soft tissue thickness at the thyrohyoid membrane level, and (3) hyomental distance ratio (HMDR), calculated as the ratio of hyomental distance in full extension (HMDe) to hyomental distance in neutral position (HMDn). These ultrasonographic parameters will be correlated with intraoperative Cormack-Lehane laryngoscopy grade and Han Scale mask ventilation score to assess their predictive value for difficult airway in obese patients.

Obese Patients Undergoing General Anesthesia

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adult obese patients (BMI \>30 kg/m², aged 18-65 years, ASA I-III) scheduled for elective surgery requiring orotracheal intubation under general anesthesia at Fatih Sultan Mehmet Training and Research Hospital, Istanbul, Turkey.

You may qualify if:

• Age 18-65 years
• BMI \>30 kg/m2
• ASA physical status I, II, or III
• Scheduled for elective surgery requiring orotracheal intubation under general anesthesia
• Written informed consent obtained

You may not qualify if:

• Emergency surgery
• History of previous head and neck surgery or radiotherapy
• Known or anticipated difficult airway (history of difficult intubation)
• Presence of cervical spine pathology or limited neck mobility
• Presence of oropharyngeal or laryngeal pathology
• Pregnancy
• Patients with tracheostomy
• Refusal to participate

Sponsors & Collaborators

• Fatih Sultan Mehmet Training and Research Hospital: lead

Study Sites (1)

Fatih Sultan Mehmet Training and Research Hospital

Istanbul, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Obesity

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Central Study Contacts

Emin Mert Koyutürk, MD

CONTACT

+905362403394; mertkytrk@gmail.com

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Anesthesiologist, Principal Investigator

Study Record Dates

• First Submitted: March 27, 2026
• First Posted: April 14, 2026
• Study Start: April 10, 2026
• Primary Completion (Estimated): October 10, 2026
• Study Completion (Estimated): November 1, 2026
• Last Updated: April 14, 2026

Record last verified: 2026-04

Locations

TU (1)